A technique exists of displaying the amount of carbon dioxide emitted with respect to electricity consumption to prompt users to minimize their carbon dioxide emissions (see, for example, JP-A [KOKAI] No. 2008-97303).
However, merely displaying the amount of emitted carbon dioxide does not directly minimize emissions, since reduction of emissions depends on what actions users actually take on the basis of the displayed amount. In the control of domestic electrical appliances and electricity supply subsystems, there is no method for minimizing carbon dioxide emissions. In particular, in a mixed electricity supply environment involving solar energy, fuel cells, wind power, and micro-grid equipment, there is no demand-side control method capable of dealing with a continuously varying energy mix. Accordingly, there is no method of promoting efficient demand-side actions or of effectively using surplus electricity generated by micro-grid devices (mismatch between supply and demand associated with micro-grid devices).